Regional variation in hip fracture incidence among Japanese hemodialysis patients

Hip fracture incidence in Japanese hemodialysis patients is five-fold higher than in the general population, although the mechanisms underlying this difference are not fully understood. Substantial regional variation exists in hip fracture incidence in the general Japanese population, despite a uniform health care and insurance system and lack of ethnic and racial variation. In this study, we determined whether the regional variation seen in the general population also applies to hemodialysis patients in Japan. Standardized incidence ratios were calculated for each regional district, and regional variations of hip fracture incidence among hemodialysis patients were evaluated using data obtained from the Japanese Society for Dialysis Therapy registry (data collected from December 2007 to December 2008). Standardized hip fracture incidence ratios across the districts ranged from 0.71 to 1.29 for male and 0.49 to 1.36 for female hemodialysis patients. Incidence ratios tended to be higher in western Japan and lower in eastern Japan, suggesting that regional variation also exists among hemodialysis patients. Our findings suggest that common risk factors for hip fracture may be shared among the general population and hemodialysis patients. Further research aimed at identifying factors, including those associated with regional variation, may help decrease hip fracture incidence in both the general population and hemodialysis patients in Japan.